A New Species Of Amphipod (Crustacea : Amphipoda : Lysianassoidea) From The Pacific Coast Of North America

6 Pages·1998·2 MB·

by  A Dalkey

PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
lll(3):621-626. 1998.
A new species of amphipod (Crustacea: Amphipoda: Lysianassoidea)
from the Pacific Coast of North America
Ann Dalkey
Environmental Monitoring Division, City of Los Angeles, 12000 Vista Del Mar,
Playa del Rey California 90293, U.SA.
—
Abstract. A new species of lysianassoid amphipod, Lepidepecreum serra-
culum, is described. This species possesses a distinctive rudder-shaped convex
carination of urosomite 1 that combined with a slightly carinate antenna 1,
chelate gnathopod 2, and rounded comers ofthe epimera, distinguishes it from
other species of Lepidepecreum. It occurs in a variety of substrata subtidally
m
to 150 depth from the Mexican-American border to Alaska.
An undescribed species of the lysianas- 523.1. Paratypes: Huntington Beach, Cali-
soid amphipod Lepidepecreum has been en- fornia, County Sanitation Districts of Or-
countered regularly in sublittoral surveys ange County Station B4, 17 Jul 1980,
m
conducted in southern California during the 33°34.54'N, 117°59.75'W, 60 depth, one
LACMNH
past 20 years. This species was first rec- female, No. 80-162.1, Station
ognized by Barnard (1969) who compared B0(1) 5 Feb 1980 33°34.67'N, 118°00.54'W
it with several Lepidepecreum species in- 60 m depth, one female, LACMNH No 80-
cluding Lepidepecreum gurjanovae Hurley, 163.1, and Station Control(l), 15 Jan 1981,
m
1963. Barnard, noting that his specimens 33°35.95'N, 118°03.79'W, 60 depth, one
differed morphologically from L. gurjano- female, LACMNH No 81-240.1; Santa
vae and occurred in much shallower water, Monica Bay, City ofLos Angeles, Environ-
listed his material as Lepidepecreum ? gur- mental Monitoring Division Station D3,
janovae pending further study. Subsequent- 33°51.78'N, 118°35.25'W, 24 Jan 1994, 78
ly, during Southern California Association m depth, one female, LACMNH No 94-90.1
of Marine Invertebrate Taxonomists and Station E8, 33°54.30'N, 118°36.43'W,
m
(SCAMIT) workshops conducted with the 29 Jul 1993, 151 depth, two males,
late J. Laurens Barnard, the species was LACMNH No—93-143.1.
recognized as distinct, both morphological- Diagnosis. Coxae and pereopods 5-7
ly and ecologically. It was listed as Lepi- ornamented with fine setules. Antenna 1,
A
depecreum sp. priorto formal description article 1 slightly carinated, callynophore
(SCAMIT 1996). present in males. Metasomite 3 with pos-
terodorsal carina. Urosomite 1 with pro-
Lepidepecreum serraculum, new species nounced rudder-shaped carina. Mandible
Figs. 1-3 with moderately developed setulose molar.
— Maxilla 1 outerplate spines well developed.
Materialexamined. All specimenshave Gnathopod 2 minutely chelate. Pereopods
been deposited in the Los Angeles County 5-7 article 2 posterior margins moderately
Museum of Natural History. Holotype: serrate. Epimeron 3 posterior margin
male, Santa Monica Bay, City of Los An- straight with rounded posteroventral comer.
geles, Environmental Monitoring Division, Uropods and t—elson spinose.
station DNS, 33°51.02'N, 118°25.00'W, 7 Description. Male, body smooth with
Feb 1986, 22 m depth, LACMNH No 86- thick white integument, metasomite 3 bear-
622 PROCEEDINGS OFTHE BIOLOGICAL SOCIETY OF WASHINGTON
ing posterodorsal carina, urosomite 1 with article 2 longest with setae on inner margin
pronounced rudder-shaped carina (Figs, la, and a distal seta on outer margin, article 3
b). Coxae 1-4 longer than broad, slightly similar to article 2 though shorter and bear-
expanded distally (ventrally), partially cov- ing several distal setae, article 4 covered
ered with fine setules and bordered with with striations or possibly short setules (not
many setules; coxa 4 excavate posteriorly. illustrated), prominent apicomedial seta on
Head subequal in length to first pereon- outer margin and small terminal nail (Fig.
ite, lateral lobes ofhead strongly produced, Ih).
elongate eyes with deep reddish-brown pig- Gnathopod 1 subchelate; dactyl with
mented ommatidea in alcohol. Antenna 1 proximal tooth that forms a bifid process;
short; peduncle robust, article 1 dorsal mar- article 6 sub-rectangular with distal setae,
gin carinate bearing plumose setae dorsally palmar margin bearing 2 medial teeth, ter-
and on distoventral comer, article 2 half as minating with 2 or more spines, dactyl with
long as article 1, article 3 one third as long subterminal tooth; article 5 subequal in
as article 1; accessory flagellum with 4 ar- length to article 6; articles 3 and 4 short,
ticles; main flagellum longerthan peduncle, subequal with distal setae; article 2 as long
article 1 with callynophore ofaesthetascs as as articles 3-6 combinedbearing several se-
long as the accessory flagellum (Fig. Ic). tules along anterior margin and setae on
Antenna 2 long, nearly as long as body distoposterior corner (Fig. 2a). Gnathopod
length; 8 setae subapically on outer ventro- 2 minutely chelate; dactyl small, triangular
lateral margin of peduncular article 3, arti- bearing a single seta; article 6 anterior mar-
cles 4 and 5 both possessing a row of se- gin convex bearing 3 rows of serrate setae,
tules on dorsal margin and single plumose lower margin straight, terminating in tooth
seta on anteroventral comer; flagellum at armed with small spines; article 5 twice as
least 60-articulate, the first 40 calceolate long as article 6, anterior margin convex
(Fig. Id). Epistome broadly rounded pro- with many fine setules and setae distally,
duced above upper lip. Mandible with mod- posterior margin expanded distally covered
erately developed setulose molar, row of with a rasp ofmany scales; article 4 shorter
raker spines, incisor well defined with con- than article 5, expanded distally with prom-
vex cutting edge; palp proximal to molar, inent anterior setae; article 3 length sub-
3-articulate, article 1 short, article 2 long equal to article 5; article 2 length subequal
bearing distal spines, article 3 half as long to combined length of articles 3-6 (Fig.
as article 2 with inner and distal spines (Fig. 2b). Pereopod 3 simple; locking spines on
le). Maxilla 1: inner plate bearing distal distal end of article 6, article 4 expanded
plumose setae and many fine hair-like setae; along anterior margin (Fig. 2c). Pereopod 4
outer plate with 11 multicuspidate spine- similar to pereopod 3 in size and shape
teeth; palp 2-articulate, article 2 longerhav- (Fig. 2d). Pereopod 5 shorter than pereo-
ing small distal teeth and a seta (Fig. If). pods 3 and 4; article 4 expanded distopos-
Maxilla 2: inner plate with row offine hair- teriorly, lobe reaching over nearly half of
like setae on inner proximal margin, several article 5; article 2 ovoid, covered with fine
setae and serrated spines on inner distal setules, posterior margin moderately ser-
margin; outer plate bearing closely bundled rate; coxa subquadrate, covered with fine
setae and serrate spines distally (Fig. Ig). setules and short spines (Fig. 2e). Pereopod
Maxilliped: inner plate with apical stout 6 length subequal to pereopod 5; article 4
teeth and spines on distal margin and plu- expanded distoposteriorly; article 2 ovoid
mose setae along inner margin; outer plate with posterior margin moderately serrate
bearing basal setae, peg-like spines along (Fig. 2f). Pereopod 7 shorter than pereo-
the inner margin and small facial spines ad- pods 5 and 6; article 4 also expanded dis-
jacent to peg-like spines; palp 4-articulate, toposteriorly; article 2 subquadrate, length
VOLUME NUMBER
111, 3 623
Fig. 1. Lepidepecreum serraculum, new species: a, entire holotype with antenna 2 placed outside coxal
plates to illustrate relative length; b, urosome; c, antenna 1; d, antenna 2; e, mandible; f, maxilla 1; g, maxilla
2; h, maxilliped.
624 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
Fig. 2. Lepidepecreumserraculum, new species: a, gnathopod 1; b, gnathopod 2; c, pereopod 3; d, pereopod
4; e, pereopod 5; f, pereopod 6; g, pereopod 7.
VOLUME NUMBER
111, 3 625
^ X. B
D
Fig. 3. Lepidepecreum serraculum, new species: a, uropod 1; b, uropod 2; c, uropod 3; and d, telson.
subequal to articles 4-7 combined, poste- lacking callynophore; antenna 2 lacking
rior margin moderately serrate with small, calceoli; uro—pod 2 lacking plumose setae.
distoposterior excavation that varies in de- Remarks. Other species differ from L.
gree among and within individuals (Fig. serraculum in cuticle ornamentation, body
2g). and antenna 1 carination, gnathopod che-
Epimera 1-2 posteroventrally convex; lation, pereopods 5-7 serration, uropod and
epimeron 3 (Fig. la) posterior margin telson spination. Lepidepecreum. serracu-
straight with rounded posteroventral comer. lum is most similar to L. gurjanovae which
Uropod 1 long; peduncle dorsally excavate differs from the former by possessing for-
with spinose margins; spinose rami slightly ward directed carination on article 1 of the
shorter than peduncle, both with spines and first antennal peduncle, a sub-chelate
subterminal nail (Fig. 3a). Uropod 2 shorter gnathopod 2, carination on all pereonites,
than uropod 1; peduncle dorsally excavate subrectangular epimeron 3 pleon epimeron,
with spines and setules on margins; rami and upturned carination of urosomite 1
spinose and subequal in length, both with (Hurley 1963). Although their geographic
subterminal nail (Fig. 3b). Uropod 3 pedun- ranges overlap in the northeastern Pacific,
cle shorter than uropod 1 peduncle, deeply the species are separated bathymetrically
excavate dorsally with setae on outer face {Lepidepecreum serraculum subtidal to 150
and spines on medial margin; inner ramus m, L. gurjanovae >260 m). Another north-
subequal to peduncle in length, foliaceous, eastern Pacific species L. garthi differs
bearing setules on the proximal-lateral mar- from L. gurjanovae by the absence ofeyes,
gin and spines on the apicolateral margin; forward directed carina on article 1 of the
outer ramus longer, foliaceous with many first antennal peduncle, pronounced cari-
plumose setae on beveled apicolateral mar- nation on all body segments, subchelate
gin (Fig. 3c). Telson as long as uropod 3 gnathopod 2, and fewer uropod and telson
outer ramus, longer than broad, incised spines (Hurley 1963). Other northeastern
three-fourths of its length, each lobe taper- Pacific species L. comatum and L. vitjazi
ing distally, each with small apical plumose differ from L. serraculum by possessing a
seta, apical spines and subterminal spine coarser cuticle ornamentation; L. alectum
and setule (Fig. 3d). and L. kasatka by lacking carination on an-
Female, non-ovigerous: Like male but tenna 1; L. eoum and L. rostratum by pos-
antenna 1 short, flagellum only 6-articulate, sessing greater body carination; andL. nau-
626 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
tilus and L. umbo in differing body cari- plied encouragement after reviewing the
nation and by lacking uropods and telson first written draft. Conaments from Charles
spines (Gurjanovae 1962, Hirayama 1985, Oliver Coleman and three additional re-
Barnard and Karaman 1991). viewers resulted in significant improve-
A freshly preserved Lepidepecreum ser- ments to this manuscript. This paper was
raculum specimen had orange-pink dots at partially funded by SCAMIT Grant Num-
the base of coxal plates 1-3 and 5; orange- ber 98-1 and is SCAMIT Contribution
pink dots on the dorsum of pereonites 1—9 Number 13.
including a ba—nd across pereonite 8.
Etymology. The specific epithet serra- Literature Cited
culum is a Latin neuter noun, meaning rud-
Barnard, J. L. 1969. Gammaridean amphipoda of the
der, and is placed in apposition with the ge- rocky int—ertidal ofCalifornia: Monterey Bay to
neric name. It alludes to the easily recog- LaJoUa. Bulletin ofthe United StatesNation-
nizable rudder-shaped dorsal carina on uro- al Museum 258:1-230.
somite 1. — , & G. S. Karaman. 1991. The families and
Distributional ecology. This species generaofmarine gammaridea—nAmphipoda(ex-
cept marine Gammaroids). Records of the
occupies a wide range and variety of habi- Australian Museum, Supplement 13(Part 2):
tats. It occurs from the Mexican-American 419-866.
border and extends north along the Pacific Gurjanovae, E. E 1962. Bokoplavy severnoi chasti
Coast to Alaska. Typical specimens from Tixogo —Okeana (Amphipoda-Gammaridea)
southern California are 3 mm in length chast' 1. Akademii Nauk SSSR, Opredeliteli
po Faune SSSR 74:1-440.
whereas those from northern range of dis- Hirayama, A. 1985. Taxonomic studies on the shallow
tribution are twice as long (Norma Jarrett, water Gammaridean amphipoda of West Kyu-
pers. comm.). It is found in sediments rang- shu, Japan. V. Leucothoidea, Liljeborgiidae,
ing from fine (sandy silt) to coarse (red Lysianassidae {Prachynella, Aristias, Ensayar—a,
Lepidepecreum. Hippomedon and Anonyx).
sands), off open ocean coast lines and in
Publication ofthe Seto Marine Biological Lab-
harbors. Depth range is from intertidal to oratory 30:167-212.
150 m. Hurley, D. E. 1963. Amphipoda of the family Lysi-
anassidae fro—m the west coastofnorth andcen-
Acknowledgments tral America. Allan HancockFoundationPub-
lications, Occasional Paper 25:1-165.
Special appreciation is extended to Ms. Southern California Association of Marine Inverte-
Norma Jarrett, who helped me in my initial brate Taxonomists (SCAMIT). 1996. A taxo-
nomic listing of soft bottom macro- and me-
efforts to identify this species and provided
gainvertebrates from infaunal and epibenthic
information on the northern specimens and monitoring programs in the SouthernCalifornia
to the late Dr. J. Laurens Barnard, who sup- Bight. Edition 2, San Pedro, California, 86 pp.